Abstract We are requesting funds to support a major upgrade to a 7T small-animal Bruker Biospec magnetic resonance imaging (MRI) instrument that serves as the only high-field, small-animal MRI system in southern Arizona. The system was purchased in 2005 using funds from an NIH SIG award and the University of Arizona. Since then, it has served as a core facility for many investigators at the University of Arizona as well as for collaborators at other institutions. It has been a heavily used and highly-productive instrument and has been essential for many NIH-funded research projects employing small animal models. The current system is now outdated and not fully compatible with cutting-edge MRI methodology and state-of-the-art experimental application. We are proposing to upgrade most of the electronics and software of the system but continue to use the parts that are functional and compatible with the upgrade (e.g. magnet, gradients, RF coils, and RF amplifiers). This is cost- effective while maintaining instrument performance. An MRI-compatible positron emission tomography (PET) insert was recently purchased, solely through institutional funds, which has expanded the capabilities of the MRI system and intensified the need for the requested upgrade. This upgrade will immediately benefit 12 projects from 11 major users and will be an ongoing resource for many more NIH-funded research projects in the years to come. This upgrade is being strongly supported by the University. Specifically, the University is covering the costs to site the upgraded instrument in a new Bioscience Research Laboratory building, which will house a comprehensive small animal imaging facility that includes instrumentation for MRI, PET, Computed tomography (CT), Single Photon Emission Computed Tomography (SPECT), ultrasound, bioluminescence and fluorescence imaging, among others. The University is also providing technical, veterinary, and administrative support to ensure optimal function and utilization of the upgraded instrument.